Vacuum induced healing of open wounds has recently been popularized by Kinetic Concepts, Inc. of San Antonio, Tex., by its commercially available V.A.C.® product line. The vacuum induced healing process has been described in commonly assigned U.S. Pat. No. 4,969,880 issued on Nov. 13, 1990 to Zamierowski, as well as its continuations and continuations in part, U.S. Pat. No. 5,100,396, issued on Mar. 31, 1992, U.S. Pat. No. 5,261,893, issued Nov. 16, 1993, and U.S. Pat. No. 5,527,293, issued Jun. 18, 1996, the disclosures of which are incorporated herein by this reference. Further improvements and modifications of the vacuum induced healing process are also described in U.S. Pat. No. 6,071,267, issued on Jun. 6, 2000 to Zamierowski and U.S. Pat. Nos. 5,636,643 and 5,645,081 issued to Argenta et al. on Jun. 10, 1997 and Jul. 8, 1997 respectively, the disclosures of which are incorporated by reference as though fully set forth herein.
These patents, and others, addressed the problems associated with closure of many types of wounds, including large or infected wounds. Wound closure typically involves the migration of epithelial and subcutaneous tissue towards the center of the wound site. In many wounds however, this migration is slowed or non-existent due to the size of the wound, and the degree of infection. Such wounds have been commonly closed using sutures or staples, with varying results. Improved techniques, as those described in the above mentioned patents, involve applying a negative pressure to the wound over an area sufficient to promote migration of epithelial and subcutaneous tissue toward the wound. Such techniques have been met with extremely positive results, and are currently being marketed and utilized by a device known as V.A.C.® (Vacuum Assisted Closure™), manufactured by Kinetic Concepts, Incorporated, of San Antonio, Tex.
One difficulty associated with the use of the V.A.C.® device, is that no suitable means for detecting the presence or kind of infection present in the wound is available, without disturbing the airtight dressing covering the wound.
Substantial work has been performed relating to the detection of microorganisms, which include spectrometers, chromatographs, and other electronic sensors for detecting the presence of microorganisms. Exemplary U.S. patents known to applicant include Lewis, et al. U.S. Pat. No. 6,017,440 issued Jan. 25, 2000; Chutjian, et al. U.S. Pat. No. 6,188,067 issued Feb. 13, 2001; Hunter, et al. U.S. Pat. No. 5,811,255 issued Sep. 22, 1998; Overton, et al. U.S. Pat. No. 5,611,846 issued Mar. 18, 1997; and Yu U.S. Pat. No. 5,583,281 issued Dec. 10, 1996; the disclosures of which are incorporated by reference herein.
As is well known to those of ordinary skill in the art, closure of surface wounds involves the inward migration of epithelial and subcutaneous tissue adjacent the wound. This migration is ordinarily assisted through the inflammatory process, whereby blood flow is increased and various functional cell types are activated. Through the inflammatory process, blood flow through damaged or broken vessels is stopped by capillary level occlusion; thereafter, cleanup and rebuilding operations may begin. Unfortunately, this process is hampered when a wound is large or has become infected. In such wounds, a zone of stasis (i.e. an area in which localized swelling of tissue restricts the flow of blood to the tissues) forms near the surface of the wound.
Without sufficient blood flow, the epithelial and subcutaneous tissues surrounding the wound not only receive diminished oxygen and nutrients, but also are also less able to successfully fight bacterial infection and thus are less able to naturally close the wound. Until the advent of vacuum induced therapy, such difficult wounds were addressed only through the use of sutures or staples. Although still widely practiced and sometimes effective, such mechanical closure techniques suffer a major disadvantage in that they produce tension on the skin tissue adjacent the wound. In particular, the tensile force required in order to achieve closure using sutures or staples may cause very high localized stresses at the suture or staple insertion point. These stresses commonly result in the rupture of the tissue at the insertion points, which can eventually cause wound dehiscence and additional tissue loss.
Additionally, some wounds harden and inflame to such a degree due to infection that closure by stapling or suturing is not feasible. Wounds not reparable by suturing or stapling generally require prolonged hospitalization, with its attendant high cost, and major surgical procedures, such as grafts of surrounding tissues. Examples of wounds not readily treatable with staples or suturing include large, deep, open wounds; decubitus ulcers; ulcers resulting from chronic osteomyelitis; and partial thickness burns that subsequently develop into full thickness burns.
As a result of these and other shortcomings of mechanical closure devices, methods and apparatus for draining wounds by applying continuous negative pressures have been developed. When applied over a sufficient area of the wound, such negative pressures have been found to promote the migration toward the wound of epithelial and subcutaneous tissues. In practice, the application to a wound of negative gauge pressure, commercialized by Assignee or its parent under the designation “Vacuum Assisted Closure” (or “V.A.C.®”) therapy, typically involves the mechanical-like contraction of the wound with simultaneous removal of excess fluid. In this manner, V.A.C.® therapy augments the body's natural inflammatory process while alleviating many of the known intrinsic side effects, such as the production of edema caused by increased blood flow absent the necessary vascular structure for proper venous return.
While V.A.C.® therapy has been highly successful in the promotion of wound closure, healing many wounds previously thought untreatable, some difficulty remains. Because the very nature of V.A.C.® therapy dictates an atmospherically sealed wound site, it is difficult to detect the presence or concentration of contaminant microorganisms, such as bacteria, that may be present in the wound site, without removing the wound dressing. It has heretofore been necessary to disturb the wound site, and thereby interrupt the therapy, in order to test for the presence or concentration of bacterial infection. Furthermore, any disturbance to the wound site may increase the possibility of infection to the wound site. Additionally, removal of the wound dressing may cause pain or discomfort to the patient.
Accordingly, a primary object of the present invention is to provide a vacuum assisted closure device that utilizes a means for detecting the presence of an infection present at a wound site during utilization of an airtight dressing, without disturbing the dressing at the wound site.
A further object of the present invention is to provide a means for identifying the nature or specific type of infection present at a wound site during the utilization of an airtight dressing, without disturbing the dressing at the wound site.
It is yet a further object of the present invention to provide a means for detecting the concentration of an infecting agent present at a wound site during utilization of an airtight dressing, without disturbing the dressing at the wound site.